Read here and ask for more safety when you drive your motorcycle!
Whenever we decide to upgrade our bike we want to have more performance, new exhaust system and more engine power, but we do not think that then we must stop the bike with all that power.
Today we will see what are the most important parameters in a brake system: braking power, modulation and fatigue.
When we brake decisively with the front brake, on the front wheel there is a load of about 40% of rider and motorcycle weight. The friction between the front wheel and the asphalt depends proportionally on the load on the front wheel. So, if we brake decisively when the load is only 40% of the total weight, the front wheel can be blocked. In this case, the braking limit is given by the grip of the tire on the ground. The friction at this time will be quite low, because we did not give time to the fork to compress. If we give time to the fork to compress, part of the load at the rear will move to the front.
If we brake more progressively instead, after the first impulse on the brake lever, the load transfer will increase the load on the front wheel and it will limit the possibility of locking the wheel, making possible a much greater total deceleration.
The new brake system for Harley Davidson XG Street Rod allows a less abrupt attack and gradually increases its braking power.
The brake calipers are made by Brembo, a leading company in the sector, and consists of 4 braking calipers pistons, which then replaces the dual pistons system featured as standard in the XG Street Rod. Using a 4-braking calipers pistons it is possible to have a greater useful diameter of the braking band, as you can see in the drawing:
In this drawing you can see that a more external surface of the braking band is involved in the slowing down of the front wheel. Using these calipers, with the same size of the disc and with the same force applied to the brake lever, the wheel can slow down more decisively.
To explain this behavior, we have to think of the wheel as a large disk that advances with a certain inertia.
To slow down the wheel you need a braking torque.
The torque capacity of a brake rotor can be expressed as 𝑇 = 𝜇 ∗ 𝐹 ∗ 𝑟
where 𝜇 is the coefficient of friction, F is force on each pad and r is the mean radius that is the distance between the center of the wheel and the center of the pad.
With four braking calipers pistons it is possible to obtain the same original friction surface moving in a larger diameter, as shown in the drawing. With this solution we are able to slow down the wheel more effectively at the same pressure on the brake lever.
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